Dynamic spatiotemporal activation of a pervasive neurogenic competence in striatal astrocytes supports continuous neurogenesis following injury

Adult neural stem cells (NSCs) are conventionally regarded as rare cells restricted to two niches: the subventricular zone (SVZ) and the subgranular zone. Parenchymal astrocytes (ASs) can also contribute to neurogenesis after injury; however, the prevalence, distribution, and behavior of these latent NSCs remained elusive. To tackle these issues, we reconstructed the spatiotemporal pattern of striatal (STR) AS neurogenic activation after excitotoxic lesion in mice. Our results indicate that neurogenic potential is widespread among STR ASs but is focally activated at the lesion border, where it associates with different reactive AS subtypes. In this region, similarly to canonical niches, steady-state neurogenesis is ensured by the continuous stochastic activation of local ASs. Activated ASs quickly return to quiescence, while their progeny transiently expand following a stochastic behavior that features an acceleration in differentiation propensity. Notably, STR AS activation rate matches that of SVZ ASs indicating a comparable prevalence of NSC potential.